Electric winding body and transformer having forced cooling

ABSTRACT

An electrical winding body includes an electrically conductive winding and an insulation surrounding the winding. The surrounding insulation surrounds the entire winding and forms a mechanically stable winding body. At least one continuous channel having an opening in the electrical winding body is disposed inside the winding body. An extension element is placed in the openings of the continuous channels to elongate the channels beyond the dimensions of the electrical winding body, thus providing for improved cooling. Side elements are additionally attached on the outer wall of the electrical winding body to create an intermediate space which forms a new cooling channel that produces an additional cooling effect due to an air current created by the chimney effect.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to an electrical winding body having anelectrically conductive winding and insulation surrounding the winding,wherein the surrounding insulation surrounds the entire winding andforms a mechanically robust winding body, and at least one continuouschannel having an opening in the electrical winding body is arrangedwithin the electrical winding body. The invention also relates to atransformer having an electrical winding body according to theinvention. The electrical winding bodies are part of a transformer.

The thermal load on a transformer, in particular a cast-resintransformer, has a considerable influence on the life of thetransformer. Adequate cooling of the windings is therefore essential inparticular for air-cooled transformers, such as cast-resin transformers.

By way of example, EP 0092204 A2 describes an induction coil wherein,according to the invention there, cooling channels are arranged betweenthe winding, and are used to cool the winding. According to theinvention there, an insulation cylinder is likewise arranged around thewinding, for electromagnetic shielding.

Furthermore, DE 37 32 670 A1 discloses an arrangement of a transformerand of a pylon in an overhead line system for electricity transmission.According to the invention there, an air-cooled transformer is used inan overhead line pylon, wherein the part of the pylon which is aboveground level is in the form of a chimney, and the transformer issupported, under the transformer, on a pylon foot.

Furthermore, laid-open specification DE 27 13 183 describes an apparatusfor cooling a transformer. Corresponding to the invention there, atransformer is provided having an attachment or an insert such that theheat which is created throughout the entire transformer and in thetransformer internal area above the insert can be carried away by thechimney-like attachment.

The solutions known from the prior art have the disadvantage thatextensive structural components must for this purpose be arranged aroundthe transformer and/or fitted in the transformer station. Upgrading ofan existing transformer with cooling channels, in particular of acast-resin transformer, is, according to the solutions known from theprior art, possible only by extensive design measures, and in many casesno appropriate physical space is available around the transformer.

BRIEF SUMMARY OF THE INVENTION

The object of the present invention is therefore to provide improvedcooling, which can be implemented easily, for a transformer with coolingchannels.

The invention provides that an extension element directly surrounds theopening of the continuous channel on the surface of the electricalwinding body and the continuous channel beyond the external dimensionsof the electrical winding body is thus lengthened. The extension of thecooling channel and/or of the internal recess in the electrical windingbody by means of the extension element beyond the external dimensions ofthe electrical winding body reinforces the so-called chimney effectwithin the cooling channels. This ensures a greater air flow rate andtherefore improved cooling through the cooling channels. The extensionof the inner or outer area of the electrical winding body likewiseresults in improved cooling between the inner windings and the core,which can be arranged in the interior of the electrical winding body.

The use of the extension element for fitting around the opening of thecontinuous channels in the electrical winding body allows existingtransformers, in particular cast-resin transformers, to be retrofittedsimply and quickly, thus ensuring improved cooling. The presentinvention therefore makes it possible to considerably extend theoperating life of the transformer.

In contrast to the solutions in the prior art, according to the presentinvention, only the air circulation within the cooling channels isimproved, and in fact this does not lead to complex convection patternsof the solutions known in the prior art. In fact, in the prior art, thedifferent temperature and flow conditions on the upper face of thetransformers lead to a very complex convection pattern above the entiretransformer, which can impede forced air cooling. The alternatingsequence of the openings of the cooling channels in conjunction with thesurrounding solid upper material of the heated winding body thusproduces a complex convection pattern of the air above the entireelectrical winding body. In the case of a polyphase transformer, the airflows above the various electrical winding bodies in the transformeradditionally influence one another such that no air flow directedexclusively upward occurs above the continuous channels in thetransformer.

The present invention ensures that a forced flow of the cooling medium,for example air, occurs only within the cooling channels. Thetemperature and flow patterns of the air at the end of the extensionelement actually no longer influence the temperature and flow conditionson the immediate surface of the electrical winding body to the sameextent as the solutions in the prior art.

One advantageous refinement of the electrical winding body provides thatthe extension element can be pushed into the continuous channel. The useof an elastic extension element provides the capability to insert theextension element into the channel with virtually correspondingdiameters of the channel and of the extension element, and in this wayto ensure simple retrospective installation of the extension element onthe transformer.

Alternatively, the extension element is designed such that, with respectto the longitudinal axis of the extension element, the extension elementis in the form of a cylinder and has two overlapping ends in thelongitudinal direction. The overlap of the ends in the longitudinaldirection of the cylinder ensures that the diameter of the extensionelement can be varied to a major extent without adversely affecting thecylindrical shape, and thus ensuring a chimney effect. The electricalcharacteristics of the extension element are in this case chosen suchthat the open cylinder on its own increases the cylinder radius and canthus be fixed to the inner wall of the continuous channel, without anyfurther aids, when it is inserted within the continuous channel.

In order to improve the through-flow of the cooling medium, andtherefore force the chimney effect, the extension element has adifferent cross section and/or diameter with respect to the longitudinalaxis. The extension element is advantageously likewise at leastpartially inclined—with respect to the longitudinal axis of theextension element. The partial inclination of the extension elementmakes it possible to also guide the channel beyond the dimensions of theelectrical winding body in the case of a physically poor arrangementabove the electrical winding body. In particular, the extensions of thechannel around a yoke which is located above the electrical winding bodycan be ensured by means of an appropriate angled configuration of theextension element.

The extension element is advantageously manufactured from an elasticand/or flexible material.

In order to assist the vertical movement of the cooling medium throughthe continuous channels, which are likewise arranged vertically, theconnecting element is arranged on at least one of the end faces—withrespect to the longitudinal axis of the electrical winding body. Inparticular, the arrangement of the extension element above or below theelectrical winding body ensures that the vertical channel path isextended and therefore ensures improved cooling because of the chimneyeffect.

In one advantageous refinement of the electrical winding body, theextension element can be fixed by means of attachment means to theopening. Attachment of the extension element in the immediate vicinityof the opening by means of suitable attachment elements results in theextension element being connected to the electrical winding body in amechanically robust manner. By way of example, attachment means may beangled elements which are at the same time arranged on the end surfaceof the electrical winding body and on the lower face of the extensionelement.

Furthermore, it is possible to use a closure element, in which casecorresponding formed-out areas of a closure element, for example abayonet fitting, are feasible around the opening of the continuouschannel and the extension element. The extension element could then beinserted into a holder, arranged around the opening of the continuouschannel, of a bayonet fitting, and could be locked by rotation of theextension element.

In order to improve the cooling of the outer surfaces of the electricalwinding body, a side element is advantageously arranged radially on theelectrical winding body with respect to the longitudinal axis of theelectrical winding body, such that the intermediate space created inthis way results in an additionally continuous channel on the outer faceof the electrical winding body. The fitting of a side elementadvantageously provides an additional cooling channel around theelectrical winding body, and thus further improves the coolingcharacteristics.

The side element is advantageously shaped such that the cooling mediumis transported to the electrical winding body via a large air inlet, anda narrower channel, and therefore an increased chimney effect, arecreated by a short distance for this purpose between the side elementand the outer wall of the electrical winding body. The side element isadvantageously designed such that the air inlet can suck in a largeamount of air as a cooling medium, and can use this for the coolingprocess within the electrical winding body. This can be ensured by anappropriate air inlet. The air inlet can advantageously be open over theentire length, with respect to the longitudinal axis of the electricalwinding body, or may be arranged in the form of a partial opening withina side element which otherwise completely surrounds the electricalwinding body.

The air inlet is advantageously aligned in the direction of an increasedexternal air flow. When using the present invention in regions wherethere is a severe climatic influence, for example in the high seas, theair inlet can be aligned with a preferred flow direction and/or winddirection when the electrical winding body is installed in anunprotected manner in the surrounding medium. In this case, the airinlet is then used as a type of wind trap, such that the normal air flowassists the chimney effect in cooling the electrical winding body. Theside element and/or extension element are/is advantageously formed atleast partially from a plastic. This ensures simple production, and theextension element or side element can easily be fitted in or on theelectrical winding body.

The side element is advantageously attached to the outer wall of theelectrical winding body by holding elements, for example rods. Thedistance between the side element and the outer wall of the electricalwinding body can be determined by the size and shape of the holdingelements, thus defining the width and shape of the intermediate spacewhich is created in the intermediate space between the side element andthe electrical winding body. The holding element can either form a pointconnection to the electrical winding body, in the form of a rod at oneof the corners of the side element, or alternatively a large-area holdermay produce a connection to the electrical winding body for examplealong the entire longitudinal face of the side element—with respect tothe longitudinal axis of the side element.

The object is likewise achieved by a transformer having at least onecore which can be magnetized, having a yoke and having at least twolimbs, as well as at least two electrical winding bodies each having anelectrically conductive winding and insulation surrounding therespective winding, wherein the surrounding insulation surrounds therespective winding and in each case forms a mechanically robust windingbody, and an electrical winding body is arranged on one limb. Theinvention provides that at least one separating element is arrangedbetween two electrical winding bodies, wherein the separating elementcomprises at least two side elements, which can be fixed to one anotherat the rear. The capability to attach the side elements such that theycan be fixed to one another at the rear allows the separating element tobe fitted easily and retrospectively between the electrical windingbodies. The separating elements can advantageously be fitted with thecore, in particular the yoke, and/or directly to at least one windingbody.

In one advantageous refinement of the transformer, the side elements ofthe separating element can be fixed by means of at least one attachmentelement at the rear wall, wherein the force effect of the attachmentelement on the side elements influences the shape of the side elements.According to the present invention, the attachment element, inparticular a screw connection, is used not only for mutual attachment ofthe side elements which are arranged at the rear, but also for shapingand therefore matching of the side elements to the physicalcharacteristics of the intermediate space between the electrical windingbodies, and/or to the external shape of the electrical winding bodies.

The side elements of the separating element are advantageously shaped,in particular corrugated, such that the shape of the side elements canbe varied deliberately in the case of a force from the attachmentelement. The shape of the side elements can be varied continuously, andtherefore matched, by a predeterminable different force acting from theattachment element on the side elements. Different shapes of the sideelements of the separating element which are attached at the rear can beensured, with the same force acting from the attachment element, bydifferent shapes of the side elements of a separating element. For thispurpose, it is advantageous for the side elements of the separatingelement to be manufactured from an elastic material.

In one advantageous refinement of the transformer, the side elements ofthe separating element have different attachment points, such that theshape of the side elements can be varied by a force from a plurality ofattachment elements on the side elements. The relative length distancebetween specific points on the side elements, and therefore the shape ofthe side elements, can be adjusted by the fixing of a plurality ofattachment points of the side elements, for example predeterminableholes in the side elements are connected by means of variable lengthscrew connections. In order to ensure that the side elements which havebeen combined to form a separating element have a different shape, it isalso possible for a different material of the side elements to produce adifferent shape, in addition to a deviating form. By way of example, thebolts have a diameter of 15 mm and a short step, for example with adiameter of only 9 mm, at both ends. If the flexible plate material hasholes of 10 mm, for example, the short ends of the bolts can be insertedinto these holes, and the extent of the deflection of the side elementsin the direction of a circular section is governed by the length of thecylindrical 15 mm part.

In one advantageous refinement of the transformer, at least one windingbody with an extension element is part of the transformer. This providesvery effective cooling for the transformer. The separating elementsadvantageously project, like the extension elements, beyond the externaldimensions of the electrical winding bodies, in particular cast-resinwinding bodies, and ensure effective cooling of the transformer.

Further advantageous refinements of the present invention are specifiedin the dependent claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The invention will be explained in more detail in the following textusing exemplary embodiments by way of example. In this case, by way ofexample:

FIG. 1 shows a perspective view of the electrical winding body with anextension element, and

FIG. 2 shows a perspective side view of the electrical winding body withfive extension elements and one side element, and

FIG. 3 shows a plan view of a three-limb arrangement with threeelectrical winding bodies, extension elements and side elements, and

FIG. 4 shows a perspective view of the electrical winding body with oneextension element and one side element, and

FIG. 5 shows a perspective view with three extension elements andindicated continuous cooling channels;

FIG. 6 shows a perspective view of the transformer according to theinvention with three extension elements, which are cutout with respectto the yoke;

FIG. 7 shows a plan view of the separating element with a corrugatedside element and a curved side element;

FIG. 8 shows a plan view of the separating element with two curved sideelements and a plurality of attachment points.

DESCRIPTION OF THE INVENTION

FIG. 1 shows a perspective view of the electrical winding body 1 a withfeet 4 which form a gap 5 under the electrical winding body 1 a. Air canflow from below into the continuous channels 10 a, 10 b, 10 c (10 a isnot illustrated) through the gap 5. A core which can be magnetized canbe inserted into the continuous center channel 10 a (not illustrated) inthe electrical winding body 1 a, such that the electrical winding body 1a can be used as part of a transformer. An extension element 2 a can beinserted into the continuous channel 10 a and, for example, is in theform of a cylinder. The cooling medium, in particular air, can becarried away from the electrical winding body 1 a through the upperopening of the cylinder. The air passes via the gap 5 into one of thecontinuous channels 10 a to 10 c, and flows out of the opening of theextension element 2 a, by virtue of the chimney effect. The presentinvention greatly reduces and impedes any influence on the flow andconvection conditions immediately above the end surface of theelectrical winding body 1 a.

As it passes through the channel 10 a, the cooling medium absorbs theheat from the surrounding electrical winding body 1 a, thus creating achimney effect. The air that has been heated in this way flows out athigh speed through the extended opening 6 a in the continuous channel 10a. The air flow emerging from the opening 6 a is therefore passed outfurther beyond the end face of the electrical winding body 1 a, by meansof the extension element 2 a.

FIG. 2 shows the electrical winding body 1 a with feet 4 for forming atleast one gap 5 through which the air can be sucked in under theelectrical winding body 1 a. Extension elements 3 a, 3 b, 3 c, 3 d, 3 eare arranged on the upper end face of the electrical winding body 1 a.The extension elements 3 a, 3 b, 3 c, 3 d, 3 e are arranged on openingsof continuous channels 10 a, 10 b (not illustrated), and lead to forcedcooling within the continuous cooling channel 10 a, 10 b, by the coolingmedium being carried away more strongly.

By way of example, two openings 7 a, 7 b in the continuous channels 10a, 10 b are illustrated. A side element 8 a is arranged in the radialdirection—with respect to the longitudinal axis of the electricalwinding body 1 a—with holding elements 9 a, 9 b, 9 c fixing the sideelement to the outer surface of the electrical winding body 1 a.

The plan view in FIG. 3 shows three electrical winding bodies 1 a, 1 b,1 c which are at least partially surrounded by a side element 8 a, 8 b,8 c, 8 d and at least partially have extension elements 2 a, 3 a, 3 b, 3c, 3 d, 3 e. The electrical winding body 1 a for the first phase has anextension element 2 a with respect to the center channel opening 6 a inthe electrical winding body 1 a. This lengthens the channel 10 a (notillustrated) of the center opening 6 a upward. The center opening 6 acan likewise be lengthened in the direction of the base, thus resultingin an extended continuous channel 10 a, going beyond the externaldimensions of the electrical winding body 1 a. The first electricalwinding body 1 a is partially surrounded by a side element 8 a.

For the second phase of a three-limb transformer, the second electricalwinding body 1 b is not provided with an extension element. The centerelectrical winding body 1 a in fact has an air inlet 11 which is formedby the side elements 8 b, 8 c, through which the air is channeled to theelectrical winding body 1 b, and increases because of the heating withinthe electrical winding body 1 b.

The right-hand side element 8 c is directly connected to the adjacentside element 8 d of the third electrical winding body 1 c.Advantageously, the side elements 8 c, 8 d can be directly connected toone another and can be attached to a yoke, which is not illustrated. Thethird electrical winding body 1 c has a plurality of extension elements3 a, 3 b, 3 c, 3 d, 3 e, which are arranged on the end face of the thirdelectrical winding body 1 c. The extension elements 3 a, 3 b, 3 c, 3 d,3 e can be selectively inserted into the openings 7 a, 7 b in thecontinuous channels 10 a, 10 b, in such a way that there is no need foran extension element 3 a, 3 b, 3 c, 3 d, 3 e for each opening 7 a, 7 b,because of the thermal conditions within the cooling channel 10 a, 10 b.

In the chosen example shown in FIG. 3, an extension element 3 a, 3 b, 3c, 3 d, 3 e is not fitted in each cooling channel 10 a, 10 b in thethird electrical winding body 1 c.

FIG. 4 shows a perspective view of the electrical winding body 1 a withan extension element 2 a within the center opening 6 a. A side element 8a is fitted to a subsection of the outer surface of the electricalwinding body 1 a and leads to forced cooling of the outer surface of theelectrical winding body 1 a, because of the intermediate space formed inthis way. The integration of feet 4 in the electrical winding body 1 aresults in an intermediate space 5 being formed between the lower faceof the electrical winding body 1 a and the base. These measures ensurefree circulation of the air in the continuous channels 10 a, 10 b (notillustrated).

The perspective view in FIG. 5 shows an electrical winding body 1 a withan extension element 2 a of the center opening 6 a. Furthermore,extension elements 3 a, 3 b relating to the openings 7 a, 7 b, (notillustrated) are arranged on the indicated continuous cooling channels10 a, 10 b at the openings 7 a, 7 b. The example illustrated in FIG. 5results on the one hand in forced cooling within the center channel 10 aand the opening 6 a through the extension element 2 a, thus ensuringthat the innermost winding of the winding body 1 a is cooled.Furthermore, the extension elements 3 a, 3 b for the continuous channels10 a, 10 b assist forced cooling in a center winding area, thus ensuringuniform cooling of the electrical winding body 1 a.

FIG. 6 shows a perspective view of the transformer 15 according to theinvention with three extension elements 2 a, 2 b, 2 c, which are cut outwith respect to the yoke 14. A separating element 13 according to theinvention is fitted between two electrical winding bodies 1 b, 1 c, andcomprises two side elements 8 b, 8 c which are connected to one anotherat the rear. The separating element 13 is connected to the yoke 14.Furthermore, the outer side elements 8 a, 8 d likewise contribute toimproved cooling of the transformer 15. The extension elements 2 a, 2 b,2 c go beyond the yoke 14, and are cut out with respect to the yoke 14.This allows the extension elements 2 a, 2 b, 2 c to be fittedretrospectively. Furthermore, the extension elements 2 a, 2 b, 2 c maybe composed of segments which can be assembled, allow the segments ofthe extension elements 2 a, 2 b, 2 c to be mounted individually at thefront and rear, and then securely surround the yoke 14 by means of asuitable attachment.

FIG. 7 shows a plan view of the separating element 13. Two differentlyshaped side elements 8 a, 8 b are connected to one another at the rearby means of a screw connection as an attachment element 12. The shape,in particular a corrugated shape, of one of the side elements 8 b allowsthe shape of the side elements 8 a, 8 b to be varied deliberately by thepredeterminable length of the screw connection 12.

The plan view in FIG. 8 shows the shaping of the side elements 8 a, 8 bof the separating element 13 by the use of a plurality of attachmentelements 12. The deliberate placing of attachment elements 12 atselected attachment points on the side elements 8 a, 8 b, for exampleholes in the attachment points, allows the shape of the side elements 8a, 8 b, and therefore of the separating element 13, to be predeterminedby adjusting the length of the attachment elements 12, for example ascrew connection.

1. A transformer, comprising: at least one core to be magnetized; ayoke; at least two limbs; at least two electrical winding bodies eachdisposed on a respective one of said limbs, said at least two electricalwinding bodies each having an electrically conductive winding andinsulations each surrounding a respective one of said electricallyconductive windings for mechanical sturdiness of said electrical windingbodies; and at least one separating element disposed between two of saidelectrical winding bodies, said at least one separating element havingat least two side elements to be rearwardly fixed to one another; atleast one attachment element at a rear wall for fixing said at least twoside elements of said at least one separating element, said at least oneattachment element effecting a force on said at least two side elementsinfluencing a shape of said at least two side elements.
 2. Thetransformer according to claim 1, wherein said at least two sideelements of said at least one separating element having a shape to bevaried by a force from said at least one attachment element.
 3. Thetransformer according to claim 2, wherein said shape of said at leasttwo side elements to be varied is a corrugated shape.
 4. The transformeraccording to claim 1, which further comprises a plurality of attachmentelements, said at least two side elements of said at least oneseparating element having different attachment points, and said at leasttwo side elements having a shape to be varied by a force from saidplurality of attachment elements on said at least two side elements. 5.The transformer according to claim 1, wherein the transformer is acast-resin transformer.
 6. The transformer according to claim 1, whereinsaid at least one attachment element passes through said at least twoside elements.